Area specific so ask your realtor.

I would check with an appraiser in your area. To me (and I don't know your area at all) it wouldn't be considered a basement because the entire house is built on a slab above grade but you need to know from a professional in your area.

Interesting, so the definition of a basement is up to interpretation?

I had an appraiser say slab and an inspector say basement.

Is there usually an official authority I can ask in the area (county etc)?

The appraisers professional opinion is the one on which to rely. The inspector doesn't typically know about house types and whether its above or below grade as to value (if that is what you are concerned about). Inspectors are searching for working and non working condition of your home and apparent structural concerns, not house type.

AFAIK there is no official authority in the county/municipality/state that determines house type.

Nothing below grade

yes it has two entrances on the first level. 3 on the second. So still yeah, not a basement. Thanks guys